THE RELATIONSHIP BETWEEN TANNINS CONCENTRATION IN SOME COTTON VARIETIES AND SUSCEPTIBILITY TO PIERCING SUCKING INSECTS

Tannins have been implicated in the resistance of some cotton varietie s to insect attack. The relationship between tannin concentration and susceptibility of some Egyptian cotton varieties to piercing sucking i nsects has been undertaken in the present work. Eight Egyptian cotton derived from Gossypium barbadense and one variety from G. hirsutum wer e evaluated. There is a significant negative linear relationship betwe en the concentration of tannins in two Egyptian varieties, Giza 70 and Giza 76, and the population density of piercing sucking insects. On t he contrary, a positive correlation existed between piercing sucking i nsect infestation and tannin concentrations in the two cotton varietie s, Giza 80 and Giza 81. This may be attributed to the low level of tan nins in these two varieties.